Whatever version of Windows you use, there will invariably be some tips, tricks and short cuts. I suppose, Windows XP is just the same, and there are a few tips and tricks that you can consider using. Ultimately, these tips relate to how you can tweak the OS, via its very options and buttons.
To begin with, try right clicking the toolbar at the bottom. Then, click properties. This will bring up the taskbar properties screen. Here you can make changes, like hide the clock or lock the task bar in place by clicking the boxes.
Also, try selecting the adjacent tab. The start menu tab will allow you to select from two, the default and a classic style, which will be more like older versions. You can also select the customize button which will allow for further customization. You can change the icon sizes, make the smaller by selecting that option or reduce the number of programs on the start menu.
A simple short cut key, to access the start menu is on the keyboard. Usually it is located on left side and has a window icon on it. Press it, and the start menu will appear for you.
To get to the display properties quickly, first right click on the desktop. Then, on the small menu you can click on the properties tab. This will present the various display tabs and options available.
I would recommend you try downloading some skins. This will change the appearance of the desktop, and icons, like switching to the classic style. Try a Vista skin, to make XP seem like a more recent version!
At any rate, you can try out some effects by using the appearance tab, in the display box. Visit the display properties again, and select the appearance tab. Here, clicking on effects will bring up a few options that can be checked. Try changing the font to clear type. Alternatively, you can change the transition effects for menus by using the effect options available.
Another tip, make use of the system restore. For example, if you end up accidentally uninstalling an application of some sort. Instead of installing the whole program again, just restore the system to when it was installed.
There are of course, many more tips, tricks and short cuts available. There are a number of keyboard shortcuts that will access menus of some description, which you can try. The final tip, you can use the help guide on the OS to get more tips on customisation and shortcuts (windows key + f1). Overall, these are a few that you can use, to customize some aspects of the windows and desktop.